1. Field of the Invention
The present invention relates to a driving power control apparatus equipped in an engine of a vehicle. More particularly, this invention relates to an apparatus which controls vehicle driving power in such a way that the vehicle's acceleration is precisely controlled according to the acceleration demands requested by the driver.
2. Description of the Related Art
In general, despite the fact that many vehicles are subject to operation under the same environmental conditions each is manipulated in different ways according to the individual habits of different drivers. Likewise, it is also generally true that drivers demand vehicles having quick response and smooth acceleration. It is well known that the power output of an engine-mounted vehicle is controlled according to how much the driver depresses the accelerator pedal.
For instance, Japanese Unexamined Patent Publication No. Hei 4-314940 discloses the following control technique. This technique allows the angle of the linkless throttle valve (throttle angle) in an engine-mounted vehicle to be controlled in accordance with the thrust amount of the accelerator pedal by the driver (acceleration stroke). Data which determines the target acceleration corresponding to the acceleration stroke is previously stored as a map in a backup RAM. The throttle angle is controlled in such a manner that the actual acceleration of the vehicle comes to the target acceleration determined by this map. Through this control, the driving power of the vehicle is controlled. According to this control technique, a change in acceleration stroke and the actual acceleration are detected as a change in the degree of the acceleration requested by the driver. The data on the map is corrected so as to minimize the difference between the detected degree of the requested acceleration and the target acceleration. The corrected data is stored in the backup RAM again. That is, the compensation (correction) on the target acceleration is performed in accordance with the mentioned difference and the map is rewritten accordingly.
Thus, learning is executed in such a way that the data of the target acceleration matches the acceleration requested by the driver. It is therefore possible to determine the target acceleration which meets the driver's request. As a result, it is always possible to obtain the driving power which matches with the characteristic of the driver, regardless of the mental state of the driver and the driving environment, thus ensuring the desirable driving performance.
According to the above-described control technique, however, the data of the target acceleration is learned simply by compensating (correcting) the data and rewriting the map accordingly. The data of the target acceleration is merely learned just for a certain point or a certain range of the acceleration stroke. Therefore, there occurs a partial unbalance in the rewritten map which has the target acceleration compensated (corrected) only for a specific driving area. This causes partial discontinuity to the relationship formed between the acceleration stroke and the target acceleration in the rewritten map. Consequently, the result of changes made in the accelerator stroke can result in degraded control of the vehicle's driving power.